diff --git a/backend/src/routes/workspaces.ts b/backend/src/routes/workspaces.ts
index f08e2559..5aa5a638 100644
--- a/backend/src/routes/workspaces.ts
+++ b/backend/src/routes/workspaces.ts
@@ -15,11 +15,10 @@ import {
 import { resolveRuntimeBindings } from "../workspaces/bindings.js";
 import { buildInstallationContract, renderWorkspaceDocs } from "../workspaces/contracts.js";
 import {
-  isCanonicalWorkspace,
   parseWorkspaceYaml,
   serializeWorkspaceYaml,
-  validateCanonicalWorkspace,
   validateOperationalWorkspace,
+  validateWorkspaceDescriptor,
   type CanonicalWorkspace,
   type WorkspaceDescriptor,
 } from "../workspaces/schema.js";
@@ -177,7 +176,7 @@ async function importDraft(source: Buffer, config: WorkspaceRegistryConfig): Pro
   }
   try {
     const descriptor = parseWorkspaceYaml(utf8(files["workspace.yaml"]));
-    const workspace = validateCanonicalWorkspace(descriptor);
+    const workspace = validateWorkspaceDescriptor(descriptor);
     const docs = renderWorkspaceDocs(workspace);
     if (
       workspace.workspace.id !== manifest.workspace_id
@@ -231,6 +230,14 @@ function workspaceErrorStatus(code: keyof typeof SAFE_MESSAGES): number {
   return 400;
 }
 
+function validatedWorkspace(value: unknown): WorkspaceDescriptor | undefined {
+  try {
+    return validateWorkspaceDescriptor(value);
+  } catch {
+    return undefined;
+  }
+}
+
 function errorReply(reply: FastifyReply, error: unknown) {
   const code = workspaceErrorCode(error);
   const body: Record<string, unknown> = { code, message: SAFE_MESSAGES[code] };
@@ -253,7 +260,8 @@ function errorReply(reply: FastifyReply, error: unknown) {
       ) body[key] = revision;
     }
     for (const key of ["base", "local", "remote"] as const) {
-      if (conflict[key] && isCanonicalWorkspace(conflict[key] as WorkspaceDescriptor)) body[key] = conflict[key];
+      const workspace = validatedWorkspace(conflict[key]);
+      if (workspace) body[key] = workspace;
     }
   }
   return reply.code(workspaceErrorStatus(code)).send(body);
@@ -262,7 +270,7 @@ function errorReply(reply: FastifyReply, error: unknown) {
 function publishRequest(value: unknown): PublishWorkspaceRequest {
   const parsed = publishPayload.parse(value);
   if (parsed.action === "delete") return parsed;
-  return { ...parsed, workspace: validateCanonicalWorkspace(parsed.workspace) };
+  return { ...parsed, workspace: validateWorkspaceDescriptor(parsed.workspace) };
 }
 
 export function workspaceRoutes(app: FastifyInstance, deps: WorkspaceRoutesDeps): void {
@@ -321,7 +329,7 @@ export function workspaceRoutes(app: FastifyInstance, deps: WorkspaceRoutesDeps)
   app.post("/workspaces/validate", async (request, reply) => {
     try {
       const { workspace } = workspacePayload.parse(request.body);
-      const canonical = validateCanonicalWorkspace(workspace);
+      const canonical = validateWorkspaceDescriptor(workspace);
       return { workspace: canonical, contract: buildInstallationContract(canonical) };
     } catch (error) {
       return errorReply(reply, error);
@@ -365,7 +373,7 @@ export function workspaceRoutes(app: FastifyInstance, deps: WorkspaceRoutesDeps)
     try {
       const { id } = z.object({ id: workspaceId }).parse(request.params);
       const { workspace } = await deps.registry.read(id);
-      const canonical = validateCanonicalWorkspace(workspace);
+      const canonical = validateWorkspaceDescriptor(workspace);
       const bundle = await exportBundle(canonical);
       return reply
         .type("application/zip")
diff --git a/backend/src/workspaces/bindings.ts b/backend/src/workspaces/bindings.ts
index 19c070c7..dbc4784b 100644
--- a/backend/src/workspaces/bindings.ts
+++ b/backend/src/workspaces/bindings.ts
@@ -9,6 +9,7 @@ import {
   type VectorTransport,
   type WorkspaceDescriptor,
 } from "./schema.js";
+import type { DeprecatedV2Descriptor } from "./deprecated-v2-descriptor.js";
 
 export interface ResolvedEvidenceBinding {
   values: Record<string, string>;
@@ -85,7 +86,7 @@ function requiredSuffixes(
   const required = REQUIRED_SUFFIXES[role][transport] ?? [];
   const diagnostic = role === "DWH"
     ? workspace.diagnostics?.dwh_rest
-    : workspace.diagnostics?.vector_rest?.metadata;
+    : (workspace as unknown as DeprecatedV2Descriptor).diagnostics?.vector_rest?.metadata;
   return transport === "rest_api" && diagnostic?.auth === "none"
     ? required.filter((suffix) => suffix !== "API_KEY_FILE")
     : required;
@@ -107,14 +108,13 @@ export function resolveBinding(
   }
 
   const contract = buildInstallationContract(descriptor);
+  const legacy = descriptor as unknown as DeprecatedV2Descriptor;
   const variables = contract.variables.filter((variable) => variable.role === role);
   const transportVariable = variables.find((variable) => variable.suffix === "TRANSPORT");
   const supported = role === "DWH"
     ? descriptor.dwh.supported_transports
     : role === "VECTOR"
-      ? ("supported_transports" in descriptor.semantic_index.vector_store
-        ? descriptor.semantic_index.vector_store.supported_transports
-        : [])
+      ? legacy.semantic_index.vector_store.supported_transports
       : ["rest_api"] as const;
   const selectedValue = transportVariable ? env[transportVariable.name] : undefined;
   const selectedTransport = isTransport(selectedValue) ? selectedValue : supported[0];
diff --git a/backend/src/workspaces/contracts.ts b/backend/src/workspaces/contracts.ts
index eec16656..e535caa9 100644
--- a/backend/src/workspaces/contracts.ts
+++ b/backend/src/workspaces/contracts.ts
@@ -1,5 +1,6 @@
 import { validateWorkspaceDescriptor } from "./schema.js";
 import type { DwhTransport, VectorTransport, WorkspaceDescriptor } from "./schema.js";
+import type { DeprecatedV2Descriptor } from "./deprecated-v2-descriptor.js";
 
 export type InstallationRole = "DWH" | "VECTOR" | "VECTOR_WRITER" | "EMBEDDING" | "EVIDENCE";
 export type InstallationSuffix =
@@ -145,25 +146,25 @@ function evidenceVariables(
 export function buildInstallationContract(workspace: WorkspaceDescriptor): InstallationContract {
   const descriptor = validateWorkspaceDescriptor(workspace);
   const namespace = namespaceFor(descriptor);
+  const schemaVersion = Number(descriptor.workspace.schema_version);
+  const legacy = descriptor as unknown as DeprecatedV2Descriptor;
 
   return {
     workspaceId: descriptor.workspace.id,
     namespace,
     variables: [
       ...connectorVariables(namespace, "DWH", descriptor.dwh.supported_transports),
-      ...(descriptor.workspace.schema_version === 2
+      ...(schemaVersion === 2
         ? connectorVariables(
           namespace,
           "VECTOR",
-          "supported_transports" in descriptor.semantic_index.vector_store
-            ? descriptor.semantic_index.vector_store.supported_transports
-            : [],
+          legacy.semantic_index.vector_store.supported_transports,
         )
         : []),
-      ...(descriptor.workspace.schema_version === 2 && descriptor.semantic_index.vector_writer
+      ...(schemaVersion === 2 && legacy.semantic_index.vector_writer
         ? [createVariable(namespace, "VECTOR_WRITER", "API_KEY_FILE")]
         : []),
-      ...(descriptor.workspace.schema_version === 2
+      ...(schemaVersion === 2
         ? EMBEDDING_SUFFIXES.map((suffix) => createVariable(namespace, "EMBEDDING", suffix))
         : []),
       ...evidenceVariables(namespace, descriptor),
diff --git a/backend/src/workspaces/deprecated-v2-descriptor.ts b/backend/src/workspaces/deprecated-v2-descriptor.ts
new file mode 100644
index 00000000..dd5fe61e
--- /dev/null
+++ b/backend/src/workspaces/deprecated-v2-descriptor.ts
@@ -0,0 +1,52 @@
+import type {
+  CanonicalDiagnostics,
+  DwhTransport,
+  VectorTransport,
+} from "./schema.js";
+
+/**
+ * Temporary compile-time shape for legacy runtime branches that will be removed separately.
+ * It is deliberately not part of the accepted workspace descriptor schema.
+ */
+export interface DeprecatedV2Descriptor {
+  workspace: {
+    schema_version: 2;
+    id: string;
+    name: string;
+    description?: string;
+    language: "en" | "it";
+  };
+  dwh: {
+    engine: "postgres";
+    database: string;
+    schema: string;
+    port?: number;
+    timeout_ms?: number;
+    supported_transports: DwhTransport[];
+  };
+  semantic_index: {
+    vector_store: {
+      engine: "pgvector";
+      database: string;
+      schema: string;
+      collection: string;
+      dimensions: number;
+      distance: "cosine" | "l2" | "inner_product";
+      port?: number;
+      timeout_ms?: number;
+      supported_transports: VectorTransport[];
+    };
+    vector_writer?: Record<string, never>;
+    embedding: {
+      provider: "ollama_compatible" | "openai_compatible";
+      model: string;
+      dimensions: number;
+      timeout_ms?: number;
+    };
+  };
+  llm_policy: {
+    default?: `${string}/${string}`;
+    allowed: `${string}/${string}`[];
+  };
+  diagnostics?: CanonicalDiagnostics;
+}
diff --git a/backend/src/workspaces/diagnostics.ts b/backend/src/workspaces/diagnostics.ts
index af082207..5fa4fde2 100644
--- a/backend/src/workspaces/diagnostics.ts
+++ b/backend/src/workspaces/diagnostics.ts
@@ -12,9 +12,9 @@ import {
   resolveDiagnosticUrl,
   validateWorkspaceDescriptor,
   type RestDiagnosticRequest,
-  type WorkspaceV2,
   type WorkspaceDescriptor,
 } from "./schema.js";
+import type { DeprecatedV2Descriptor } from "./deprecated-v2-descriptor.js";
 import type { WorkspaceErrorCode } from "./types.js";
 import type { SemanticRuntimeConfig } from "./runtime-renderer.js";
 
@@ -543,7 +543,7 @@ export function createProductionWorkspaceDiagnoser(
     options: { writeProbe: boolean },
   ): Promise<WorkspaceDiagnostics> => {
     const descriptor = validateWorkspaceDescriptor(workspace);
-    if (descriptor.workspace.schema_version !== 3) {
+    if (Number(descriptor.workspace.schema_version) !== 3) {
       return await legacyDiagnoser(descriptor, bindings, options);
     }
     return await diagnoseSchemaV3Workspace(
@@ -618,11 +618,11 @@ function diagnosticError(code: WorkspaceErrorCode, field?: string): Diagnostic {
 }
 
 function bindingName(
-  workspace: WorkspaceDescriptor,
+  workspace: WorkspaceDescriptor | DeprecatedV2Descriptor,
   role: "DWH" | "VECTOR" | "VECTOR_WRITER" | "EMBEDDING",
   suffix: string,
 ): string {
-  const entry = buildInstallationContract(workspace).variables.find((variable) => (
+  const entry = buildInstallationContract(workspace as WorkspaceDescriptor).variables.find((variable) => (
     variable.role === role && variable.suffix === suffix
   ));
   if (!entry) throw new Error(`workspace contract is missing ${role}_${suffix}`);
@@ -798,7 +798,7 @@ async function diagnoseSchemaV3Workspace(
 }
 
 function diagnosticsForMissingBindings(
-  workspace: WorkspaceV2,
+  workspace: DeprecatedV2Descriptor,
   bindings: RuntimeBindings,
 ): Diagnostic[] {
   const missing = new Set([
@@ -815,7 +815,7 @@ function diagnosticsForMissingBindings(
 }
 
 function connectorRequest(
-  workspace: WorkspaceV2,
+  workspace: DeprecatedV2Descriptor,
   role: ConnectorRole,
   bindings: RuntimeBindings,
   timeoutMs: number,
@@ -889,7 +889,7 @@ function connectorRequest(
 }
 
 function tunnelProbeRequest(
-  workspace: WorkspaceV2,
+  workspace: DeprecatedV2Descriptor,
   role: ConnectorRole,
   bindings: RuntimeBindings,
   timeoutMs: number,
@@ -934,10 +934,10 @@ export function createWorkspaceDiagnoser(
     options: { writeProbe: boolean },
   ): Promise<WorkspaceDiagnostics> {
     const descriptor = validateWorkspaceDescriptor(workspace);
-    if (descriptor.workspace.schema_version !== 2) {
+    if (Number(descriptor.workspace.schema_version) !== 2) {
       return { activatable: false, diagnostics: [diagnosticError("workspace_not_activatable")] };
     }
-    const canonical = descriptor as WorkspaceV2;
+    const canonical = descriptor as unknown as DeprecatedV2Descriptor;
     const diagnostics = diagnosticsForMissingBindings(canonical, bindings);
     if (diagnostics.length > 0) return { activatable: false, diagnostics };
 
diff --git a/backend/src/workspaces/migrate-v2-qdrant.ts b/backend/src/workspaces/migrate-v2-qdrant.ts
index eae22d1a..5fd6c40d 100644
--- a/backend/src/workspaces/migrate-v2-qdrant.ts
+++ b/backend/src/workspaces/migrate-v2-qdrant.ts
@@ -1,7 +1,8 @@
-import { validateOperationalWorkspace, type WorkspaceV2, type WorkspaceV3 } from "./schema.js";
+import { validateOperationalWorkspace, type WorkspaceV3 } from "./schema.js";
+import type { DeprecatedV2Descriptor } from "./deprecated-v2-descriptor.js";
 
 export function migrateWorkspaceV2ToV3(
-  legacy: WorkspaceV2,
+  legacy: DeprecatedV2Descriptor,
   collection: string,
 ): WorkspaceV3 {
   return validateOperationalWorkspace({
diff --git a/backend/src/workspaces/runtime-renderer.ts b/backend/src/workspaces/runtime-renderer.ts
index 7cf48902..6fa159d8 100644
--- a/backend/src/workspaces/runtime-renderer.ts
+++ b/backend/src/workspaces/runtime-renderer.ts
@@ -4,9 +4,9 @@ import { buildInstallationContract } from "./contracts.js";
 import {
   validateWorkspaceDescriptor,
   type WorkspaceDescriptor,
-  type WorkspaceV2,
   type WorkspaceV3,
 } from "./schema.js";
+import type { DeprecatedV2Descriptor } from "./deprecated-v2-descriptor.js";
 import type { ResolvedBinding, ResolvedEvidenceBinding, RuntimeBindings } from "./bindings.js";
 export type { RuntimeBindings } from "./bindings.js";
 
@@ -216,8 +216,8 @@ export function renderRuntimeConfig(
     if (!variable) throw new Error(`workspace contract is missing ${role}_${suffix}`);
     return variable.name;
   };
-  if (descriptor.workspace.schema_version !== 2) {
-    if (descriptor.workspace.schema_version === 1) {
+  if (Number(descriptor.workspace.schema_version) !== 2) {
+    if (Number(descriptor.workspace.schema_version) === 1) {
       throw new Error("Workspace descriptor requires explicit migration to schema version 2");
     }
     const canonicalV3 = descriptor as WorkspaceV3;
@@ -290,7 +290,7 @@ export function renderRuntimeConfig(
     return stringify(renderedV3, { lineWidth: 0, sortMapEntries: false });
   }
 
-  const canonical = descriptor as WorkspaceV2;
+  const canonical = descriptor as unknown as DeprecatedV2Descriptor;
   if ([...bindings.dwh.missing, ...bindings.vector.missing, ...bindings.embedding.missing].length > 0) {
     throw new Error("runtime configuration requires complete bindings");
   }
diff --git a/backend/src/workspaces/schema.ts b/backend/src/workspaces/schema.ts
index acd635cd..2e1886d1 100644
--- a/backend/src/workspaces/schema.ts
+++ b/backend/src/workspaces/schema.ts
@@ -34,8 +34,8 @@ export interface CanonicalDiagnostics {
   embedding?: RestDiagnosticRequest & { response: { model: string; dimensions: string } };
 }
 
-interface WorkspaceMetadata<Version extends 1 | 2 | 3> {
-  schema_version: Version;
+interface WorkspaceMetadata {
+  schema_version: 3;
   id: string;
   name: string;
   description?: string;
@@ -51,50 +51,22 @@ interface WorkspaceDwh {
   supported_transports: DwhTransport[];
 }
 
-interface VectorStore {
-  engine: "pgvector";
-  collection: string;
-  dimensions: number;
-  distance: "cosine" | "l2" | "inner_product";
-  port?: number;
-  timeout_ms?: number;
-  supported_transports: VectorTransport[];
-}
-
-interface SemanticIndex<TVectorStore extends VectorStore> {
-  vector_store: TVectorStore;
-  vector_writer?: Record<string, never>;
-  embedding: {
-    provider: "ollama_compatible" | "openai_compatible";
-    model: string;
-    dimensions: number;
-    timeout_ms?: number;
-  };
-}
-
-interface WorkspaceBase<Version extends 1 | 2 | 3, TVectorStore, TDiagnostics = CanonicalDiagnostics> {
-  workspace: WorkspaceMetadata<Version>;
+interface WorkspaceBase<TVectorStore> {
+  workspace: WorkspaceMetadata;
   dwh: WorkspaceDwh;
   semantic_index: {
     vector_store: TVectorStore;
-    vector_writer?: Record<string, never>;
-    embedding: Version extends 3 ? {
+    embedding: {
       provider: "ollama_internal";
       model: "qwen3-embedding:0.6b";
       dimensions: 1024;
-      timeout_ms?: number;
-    } : {
-      provider: "ollama_compatible" | "openai_compatible";
-      model: string;
-      dimensions: number;
-      timeout_ms?: number;
     };
   };
   llm_policy: {
     default?: `${string}/${string}`;
     allowed: `${string}/${string}`[];
   };
-  diagnostics?: TDiagnostics;
+  diagnostics?: Pick<CanonicalDiagnostics, "dwh_rest">;
 }
 
 interface QdrantVectorStore {
@@ -147,17 +119,12 @@ export interface WorkspaceEvidence {
   policy: EvidencePolicy;
 }
 
-export interface WorkspaceV3 extends WorkspaceBase<3, QdrantVectorStore> {
+export interface WorkspaceV3 extends WorkspaceBase<QdrantVectorStore> {
   evidence?: WorkspaceEvidence;
 }
-export interface WorkspaceV2 extends WorkspaceBase<2, VectorStore & { database: string; schema: string }> {}
-
-/** A readable, non-operational v1 descriptor. It must be explicitly migrated before use. */
-export interface WorkspaceV1 extends WorkspaceBase<1, VectorStore & { database?: string; schema?: string }> {}
 
 export type CanonicalWorkspace = WorkspaceV3;
-export type LegacyWorkspace = WorkspaceV1 | WorkspaceV2;
-export type WorkspaceDescriptor = WorkspaceV1 | WorkspaceV2 | WorkspaceV3;
+export type WorkspaceDescriptor = WorkspaceV3;
 
 const workspaceId = z.string().regex(/^[a-z][a-z0-9-]{2,62}$/, {
   message: "workspace id must match ^[a-z][a-z0-9-]{2,62}$",
@@ -165,7 +132,6 @@ const workspaceId = z.string().regex(/^[a-z][a-z0-9-]{2,62}$/, {
 const identifier = z.string().regex(/^[A-Za-z_][A-Za-z0-9_]*$/, {
   message: "database identifiers must start with a letter or underscore",
 });
-const dimensions = z.number().int().positive().max(32_768);
 const port = z.number().int().min(1).max(65_535);
 const timeoutMs = z.number().int().positive();
 const modelReference = z.string().regex(/^[^/\s]+\/[^/\s]+$/, {
@@ -190,29 +156,6 @@ const restDiagnosticRequest = z.object({
 const dwhRestDiagnostic = restDiagnosticRequest.extend({
   response: z.object({ database: responseField, schema: responseField }).strict(),
 }).strict();
-const vectorMetadataDiagnostic = restDiagnosticRequest.extend({
-  response: z.object({
-    collection: responseField,
-    dimensions: responseField,
-    distance: responseField,
-  }).strict(),
-}).strict();
-const reversibleVectorProbe = restDiagnosticRequest.extend({
-  method: z.literal("POST"),
-  auth: z.enum(["bearer", "x-api-key"]),
-  response: z.object({ operation: responseField }).strict(),
-}).strict();
-const embeddingDiagnostic = restDiagnosticRequest.extend({
-  response: z.object({ model: responseField, dimensions: responseField }).strict(),
-}).strict();
-const diagnosticsSchema = z.object({
-  dwh_rest: dwhRestDiagnostic.optional(),
-  vector_rest: z.object({
-    metadata: vectorMetadataDiagnostic,
-    reversible_probe: reversibleVectorProbe.optional(),
-  }).strict().optional(),
-  embedding: embeddingDiagnostic.optional(),
-}).strict().optional();
 
 const dwhSchema = z.object({
   engine: z.literal("postgres"),
@@ -222,36 +165,11 @@ const dwhSchema = z.object({
   timeout_ms: timeoutMs.optional(),
   supported_transports: z.array(z.enum(DWH_TRANSPORTS)).min(1),
 }).strict();
-const embeddingSchema = z.object({
-  provider: z.enum(["ollama_compatible", "openai_compatible"]),
-  model: z.string().trim().min(1),
-  dimensions,
-  timeout_ms: timeoutMs.optional(),
-}).strict();
 const internalEmbeddingSchema = z.object({
   provider: z.literal("ollama_internal"),
   model: z.literal("qwen3-embedding:0.6b"),
   dimensions: z.literal(1024),
 }).strict();
-const vectorStoreShape = {
-  engine: z.literal("pgvector"),
-  collection: identifier,
-  dimensions,
-  distance: z.enum(["cosine", "l2", "inner_product"]),
-  port: port.optional(),
-  timeout_ms: timeoutMs.optional(),
-  supported_transports: z.array(z.enum(VECTOR_TRANSPORTS)).min(1),
-};
-const legacyVectorStoreSchema = z.object({
-  ...vectorStoreShape,
-  database: identifier.optional(),
-  schema: identifier.optional(),
-}).strict();
-const canonicalVectorStoreSchema = z.object({
-  ...vectorStoreShape,
-  database: identifier,
-  schema: identifier,
-}).strict();
 const qdrantVectorStoreSchema = z.object({
   engine: z.literal("qdrant"),
   collection: workspaceId,
@@ -420,13 +338,6 @@ function unique<T>(values: readonly T[], context: z.RefinementCtx, path: Propert
 
 function workspaceInvariants(workspace: any, context: z.RefinementCtx): void {
   unique(workspace.dwh.supported_transports, context, ["dwh", "supported_transports"]);
-  if ("supported_transports" in workspace.semantic_index.vector_store) {
-    unique(
-      workspace.semantic_index.vector_store.supported_transports,
-      context,
-      ["semantic_index", "vector_store", "supported_transports"],
-    );
-  }
   unique(workspace.llm_policy.allowed, context, ["llm_policy", "allowed"]);
 
   if (workspace.evidence?.source.type === "filesystem") {
@@ -461,50 +372,8 @@ function workspaceInvariants(workspace: any, context: z.RefinementCtx): void {
       message: "diagnostics.dwh_rest requires dwh rest_api transport support",
     });
   }
-  if (
-    workspace.diagnostics?.vector_rest
-    && (
-      !("supported_transports" in workspace.semantic_index.vector_store)
-      || !workspace.semantic_index.vector_store.supported_transports.includes("rest_api")
-    )
-  ) {
-    context.addIssue({
-      code: "custom",
-      path: ["diagnostics", "vector_rest"],
-      message: "diagnostics.vector_rest requires vector_store rest_api transport support",
-    });
-  }
 }
 
-const workspaceShape = {
-  dwh: dwhSchema,
-  llm_policy: llmPolicySchema,
-  diagnostics: diagnosticsSchema,
-};
-const WorkspaceV1Schema = z.object({
-  ...workspaceShape,
-  workspace: z.object({
-    schema_version: z.literal(1), id: workspaceId, name: z.string().trim().min(1),
-    description: z.string().trim().min(1).optional(), language: z.enum(["en", "it"]),
-  }).strict(),
-  semantic_index: z.object({
-    vector_store: legacyVectorStoreSchema,
-    vector_writer: z.object({}).strict().optional(),
-    embedding: embeddingSchema,
-  }).strict(),
-}).strict().superRefine(workspaceInvariants);
-const WorkspaceV2Schema = z.object({
-  ...workspaceShape,
-  workspace: z.object({
-    schema_version: z.literal(2), id: workspaceId, name: z.string().trim().min(1),
-    description: z.string().trim().min(1).optional(), language: z.enum(["en", "it"]),
-  }).strict(),
-  semantic_index: z.object({
-    vector_store: canonicalVectorStoreSchema,
-    vector_writer: z.object({}).strict().optional(),
-    embedding: embeddingSchema,
-  }).strict(),
-}).strict().superRefine(workspaceInvariants);
 const WorkspaceV3Schema = z.object({
   dwh: dwhSchema,
   llm_policy: llmPolicySchema,
@@ -521,7 +390,7 @@ const WorkspaceV3Schema = z.object({
     embedding: internalEmbeddingSchema,
   }).strict(),
 }).strict().superRefine(workspaceInvariants);
-const WorkspaceDescriptorSchema = z.union([WorkspaceV3Schema, WorkspaceV2Schema, WorkspaceV1Schema]);
+const WorkspaceDescriptorSchema = WorkspaceV3Schema;
 
 export function parseWorkspaceYaml(source: string): WorkspaceDescriptor {
   const documents = parseAllDocuments(source, { uniqueKeys: true });
@@ -538,46 +407,16 @@ export function validateWorkspaceDescriptor(workspace: unknown): WorkspaceDescri
   return WorkspaceDescriptorSchema.parse(workspace) as WorkspaceDescriptor;
 }
 
-export function isCanonicalWorkspace(workspace: WorkspaceDescriptor): workspace is CanonicalWorkspace {
-  return workspace.workspace.schema_version === 3;
+export function isCanonicalWorkspace(workspace: unknown): workspace is CanonicalWorkspace {
+  return WorkspaceDescriptorSchema.safeParse(workspace).success;
 }
 
-export function isOperationalWorkspace(workspace: WorkspaceDescriptor): workspace is WorkspaceV3 {
-  return workspace.workspace.schema_version === 3;
+export function isOperationalWorkspace(workspace: unknown): workspace is WorkspaceV3 {
+  return WorkspaceDescriptorSchema.safeParse(workspace).success;
 }
 
-/** Rejects readable v1 descriptors at every operational boundary until a caller migrates them. */
-export function validateCanonicalWorkspace(workspace: unknown): CanonicalWorkspace {
-  return validateOperationalWorkspace(workspace);
-}
-
-/** Rejects readable v1/v2 descriptors at every operational boundary until a caller migrates them. */
 export function validateOperationalWorkspace(workspace: unknown): WorkspaceV3 {
-  const descriptor = validateWorkspaceDescriptor(workspace);
-  if (!isOperationalWorkspace(descriptor)) {
-    throw new Error("Workspace descriptor requires explicit migration to schema version 3");
-  }
-  return descriptor;
-}
-
-/**
- * Explicitly upgrades a readable v1 descriptor. The caller must supply vector identity; the
- * transformer never derives it from DWH identity, even where both services share a database.
- */
-export function migrateWorkspaceV1ToV2(
-  workspace: WorkspaceV1,
-  vectorIdentity: { database: string; schema: string },
-): WorkspaceV2 {
-  const legacy = WorkspaceV1Schema.parse(workspace) as WorkspaceV1;
-  const identity = z.object({ database: identifier, schema: identifier }).strict().parse(vectorIdentity);
-  return WorkspaceV2Schema.parse({
-    ...legacy,
-    workspace: { ...legacy.workspace, schema_version: 2 },
-    semantic_index: {
-      ...legacy.semantic_index,
-      vector_store: { ...legacy.semantic_index.vector_store, ...identity },
-    },
-  }) as WorkspaceV2;
+  return validateWorkspaceDescriptor(workspace);
 }
 
 /** Builds a request URL only after rejecting values that can leave the declared service origin. */
diff --git a/backend/src/workspaces/types.ts b/backend/src/workspaces/types.ts
index 25349274..3017d6c7 100644
--- a/backend/src/workspaces/types.ts
+++ b/backend/src/workspaces/types.ts
@@ -16,4 +16,4 @@ export type WorkspaceErrorCode =
   | "git_auth_failed" | "git_non_fast_forward" | "git_push_rejected"
   | "connector_unavailable" | "semantic_index_incompatible";
 
-export type { WorkspaceV2, WorkspaceV3 } from "./schema.js";
+export type { WorkspaceV3 } from "./schema.js";
diff --git a/backend/test/routes-workspaces.test.ts b/backend/test/routes-workspaces.test.ts
index f5849d45..00e85ea5 100644
--- a/backend/test/routes-workspaces.test.ts
+++ b/backend/test/routes-workspaces.test.ts
@@ -15,8 +15,8 @@ import { createProductionWorkspaceDiagnoser } from "../src/workspaces/diagnostic
 import { WorkspaceRegistryError } from "../src/workspaces/git-repository.js";
 import { WorkspaceRegistry, type WorkspaceRevision } from "../src/workspaces/registry.js";
 import {
-  parseWorkspaceYaml, renderWorkspaceDocs, serializeWorkspaceYaml, validateCanonicalWorkspace,
-  type CanonicalWorkspace, type WorkspaceV2,
+  parseWorkspaceYaml, renderWorkspaceDocs, serializeWorkspaceYaml, validateWorkspaceDescriptor,
+  type CanonicalWorkspace,
 } from "../src/workspaces/schema.js";
 
 const workspace: CanonicalWorkspace = {
@@ -49,7 +49,7 @@ const workspace: CanonicalWorkspace = {
   llm_policy: { allowed: ["zai/glm-5.2"] },
 };
 
-const workspaceV2: WorkspaceV2 = {
+const workspaceV2 = {
   workspace: {
     schema_version: 2,
     id: "psd-clinical",
@@ -104,6 +104,11 @@ const workspaceV2: WorkspaceV2 = {
   llm_policy: { allowed: ["zai/glm-5.2"] },
 };
 
+const workspaceV1 = {
+  ...workspaceV2,
+  workspace: { ...workspaceV2.workspace, schema_version: 1 as const },
+};
+
 const revision: WorkspaceRevision = {
   id: workspace.workspace.id,
   commit: "a".repeat(40),
@@ -248,6 +253,31 @@ test("validates a canonical workspace and runs the injected installation diagnos
   expect(diagnose).not.toHaveBeenCalled();
 });
 
+test.each([
+  ["v1", workspaceV1],
+  ["v2", workspaceV2],
+])("rejects schema %s at validate and publish boundaries with a sanitized error", async (_version, legacy) => {
+  const registry = registryFake();
+  const app = appFor(registry);
+
+  for (const request of [
+    { url: "/workspaces/validate", payload: { workspace: legacy } },
+    {
+      url: "/workspaces/publish",
+      payload: { action: "create", workspace: legacy, baseCommit: revision.commit },
+    },
+  ]) {
+    const response = await app.inject({ method: "POST", ...request });
+    expect(response.statusCode).toBe(400);
+    expect(response.json()).toEqual({
+      code: "workspace_invalid",
+      message: "Workspace request or bundle is invalid.",
+    });
+    expect(response.body).not.toMatch(/migration_required|schema version/i);
+  }
+  expect(registry.publish).not.toHaveBeenCalled();
+});
+
 test("rejects a migration-required v2 workspace before resolving semantic diagnostics", async () => {
   const diagnose = vi.fn(async () => ({
     activatable: false,
@@ -342,12 +372,12 @@ test("returns a 409 field conflict instead of overwriting a changed workspace",
   const conflict = Object.assign(
     new WorkspaceRegistryError("workspace_conflict", "Workspace has changed"),
     {
-      fields: ["semantic_index.embedding.model"],
+      fields: ["workspace.description"],
       expected: { commit: "c".repeat(40), blob: "d".repeat(40) },
       actual: { commit: revision.commit, blob: revision.blob },
       base: workspace,
-      local: { ...workspace, semantic_index: { ...workspace.semantic_index, embedding: { ...workspace.semantic_index.embedding, model: "local/model" } } },
-      remote: { ...workspace, semantic_index: { ...workspace.semantic_index, embedding: { ...workspace.semantic_index.embedding, model: "remote/model" } } },
+      local: { ...workspace, workspace: { ...workspace.workspace, description: "Local description" } },
+      remote: { ...workspace, workspace: { ...workspace.workspace, description: "Remote description" } },
     },
   );
   const registry = registryFake({ publish: vi.fn(async () => { throw conflict; }) });
@@ -364,14 +394,12 @@ test("returns a 409 field conflict instead of overwriting a changed workspace",
   expect(res.statusCode).toBe(409);
   expect(res.json()).toMatchObject({
     code: "workspace_conflict",
-    fields: ["semantic_index.embedding.model"],
+    fields: ["workspace.description"],
     expected: { commit: "c".repeat(40), blob: "d".repeat(40) },
     actual: { commit: revision.commit, blob: revision.blob },
     base: workspace,
     remote: expect.objectContaining({
-      semantic_index: expect.objectContaining({
-        embedding: expect.objectContaining({ model: "remote/model" }),
-      }),
+      workspace: expect.objectContaining({ description: "Remote description" }),
     }),
   });
 });
@@ -450,7 +478,7 @@ function withEvidence(
   source: Partial<CanonicalWorkspace["evidence"]["source"]> & { type: "filesystem" | "http" | "s3" },
   changes: Partial<CanonicalWorkspace["evidence"]["policy"]> = {},
 ): CanonicalWorkspace {
-  return validateCanonicalWorkspace({
+  return validateWorkspaceDescriptor({
     ...workspace,
     evidence: { source, policy: changes },
   });
@@ -587,7 +615,7 @@ test.each([
 test("real publish create/update, pull, list, and read preserve a complete Evidence descriptor", async () => {
   const fixture = await createRealRouteFixture(httpEvidenceWorkspace);
   const status = await fixture.app.inject({ method: "GET", url: "/workspace-registry/status" });
-  const created = validateCanonicalWorkspace({
+  const created = validateWorkspaceDescriptor({
     ...httpEvidenceWorkspace,
     workspace: { ...httpEvidenceWorkspace.workspace, id: "research-clinical", name: "Research Clinical" },
     semantic_index: {
@@ -600,7 +628,7 @@ test("real publish create/update, pull, list, and read preserve a complete Evide
     payload: { action: "create", workspace: created, baseCommit: status.json().head },
   });
   const createdRevision = create.json().revision as WorkspaceRevision;
-  const updated = validateCanonicalWorkspace({
+  const updated = validateWorkspaceDescriptor({
     ...created,
     evidence: {
       ...created.evidence,
@@ -617,7 +645,7 @@ test("real publish create/update, pull, list, and read preserve a complete Evide
   });
   expect(update.statusCode).toBe(200);
   await realGit(fixture.author, ["pull", "--ff-only", "origin", "main"]);
-  const remotelyEdited = validateCanonicalWorkspace({
+  const remotelyEdited = validateWorkspaceDescriptor({
     ...updated,
     evidence: {
       ...updated.evidence,
@@ -742,7 +770,7 @@ test("real publish and pull fail safely when the contextual Evidence Git tree is
   const fixture = await createRealRouteFixture();
   await fixture.registry.bootstrap();
   const current = await fixture.registry.read("psd-clinical");
-  const missing = validateCanonicalWorkspace({
+  const missing = validateWorkspaceDescriptor({
     ...workspace,
     workspace: { ...workspace.workspace, id: "missing-evidence", name: "Missing Evidence" },
     semantic_index: {
diff --git a/backend/test/workspace-registry.test.ts b/backend/test/workspace-registry.test.ts
index c79f360e..bf019005 100644
--- a/backend/test/workspace-registry.test.ts
+++ b/backend/test/workspace-registry.test.ts
@@ -327,6 +327,8 @@ function persistPreStateManifest(root: string, commit: string): void {
   const envExample = "# Legacy registry artifact\n";
   const markdown = "# Legacy registry artifact\n";
 
+  chmodSync(join(snapshotDirectory, envName), 0o600);
+  chmodSync(join(snapshotDirectory, docsName), 0o600);
   writeFileSync(join(snapshotDirectory, envName), envExample);
   writeFileSync(join(snapshotDirectory, docsName), markdown);
   active.revisions = active.revisions.map(({ state: _state, ...revision }: Record<string, unknown>) => revision);
@@ -693,25 +695,19 @@ test("resets an ahead checkout after a rejected push and retries publication", a
   await expect(registry.publish(request)).resolves.toMatchObject({ id: "push-recovery" });
 });
 
-test("lists a v1 descriptor in migration-required state without rendering operational artifacts", async () => {
-  const legacyYaml = legacyV1Yaml();
+test.each([
+  ["v1", legacyV1Yaml()],
+  ["v2", legacyV2Yaml()],
+])("rejects a schema %s descriptor instead of activating it", async (_version, legacyYaml) => {
   const remote = await fixture(legacyYaml);
   const registry = new WorkspaceRegistry(config(join(remote.root, "registry"), remote.remote));
 
-  const status = await registry.bootstrap();
-  const [revision] = await registry.list();
-
-  expect(revision).toMatchObject({ state: "migration_required" });
-  await expect(registry.read("psd-clinical")).resolves.toMatchObject({
-    workspace: { workspace: { schema_version: 1 } },
-  });
-  expect(existsSync(join(remote.root, "registry", "snapshots", status.head!, "psd-clinical.env.example"))).toBe(false);
-  expect(existsSync(join(remote.root, "registry", "snapshots", status.head!, "psd-clinical.md"))).toBe(false);
+  await expect(registry.bootstrap()).rejects.toMatchObject({ code: "workspace_invalid" });
+  expect(existsSync(join(remote.root, "registry", "state", "active.json"))).toBe(false);
 });
 
-test("migrates a validated pre-state manifest and keeps its v1 workspace migration-gated", async () => {
-  const legacyYaml = legacyV1Yaml();
-  const remote = await fixture(legacyYaml);
+test("migrates a validated pre-state manifest while preserving its v3 operational state", async () => {
+  const remote = await fixture();
   const root = join(remote.root, "registry");
   const firstRegistry = new WorkspaceRegistry(config(root, remote.remote));
   await firstRegistry.bootstrap();
@@ -723,19 +719,20 @@ test("migrates a validated pre-state manifest and keeps its v1 workspace migrati
     degraded: false,
   });
   await expect(restoredRegistry.list()).resolves.toMatchObject([
-    { id: "psd-clinical", state: "migration_required" },
+    { id: "psd-clinical", state: "operational" },
   ]);
 
   const active = JSON.parse(readFileSync(join(root, "state", "active.json"), "utf8"));
   const manifest = JSON.parse(readFileSync(join(root, "snapshots", remote.initialCommit, "snapshot.json"), "utf8"));
-  expect(active.revisions[0].state).toBe("migration_required");
-  expect(manifest.revisions[0].state).toBe("migration_required");
-  expect(Object.keys(manifest.files)).toEqual(["psd-clinical.yaml"]);
+  expect(active.revisions[0].state).toBe("operational");
+  expect(manifest.revisions[0].state).toBe("operational");
+  expect(Object.keys(manifest.files).sort()).toEqual([
+    "psd-clinical.env.example", "psd-clinical.md", "psd-clinical.yaml",
+  ]);
 });
 
-test("finishes a pre-state active manifest migration after its snapshot was atomically updated", async () => {
-  const legacyYaml = legacyV1Yaml();
-  const remote = await fixture(legacyYaml);
+test("finishes a pre-state active manifest migration after its v3 snapshot was atomically updated", async () => {
+  const remote = await fixture();
   const root = join(remote.root, "registry");
   const registry = new WorkspaceRegistry(config(root, remote.remote));
   await registry.bootstrap();
@@ -743,19 +740,17 @@ test("finishes a pre-state active manifest migration after its snapshot was atom
 
   const snapshotPath = join(root, "snapshots", remote.initialCommit, "snapshot.json");
   const manifest = JSON.parse(readFileSync(snapshotPath, "utf8"));
-  manifest.revisions[0].state = "migration_required";
-  manifest.files = { "psd-clinical.yaml": manifest.files["psd-clinical.yaml"] };
+  manifest.revisions[0].state = "operational";
   writeFileSync(snapshotPath, JSON.stringify(manifest));
 
   const restoredRegistry = new WorkspaceRegistry(config(root, remote.remote));
   await expect(restoredRegistry.list()).resolves.toMatchObject([
-    { id: "psd-clinical", state: "migration_required" },
+    { id: "psd-clinical", state: "operational" },
   ]);
 });
 
 test("rejects a corrupt pre-state manifest rather than accepting it during migration", async () => {
-  const legacyYaml = legacyV1Yaml();
-  const remote = await fixture(legacyYaml);
+  const remote = await fixture();
   const root = join(remote.root, "registry");
   const registry = new WorkspaceRegistry(config(root, remote.remote));
   await registry.bootstrap();
@@ -872,32 +867,6 @@ test("a session revision lease survives stale retention scans until its manifest
   expect(existsSync(registry.snapshotPath(remote.initialCommit, "psd-clinical"))).toBe(false);
 });
 
-test("does not acquire a session revision lease for a migration_required workspace", async () => {
-  const remote = await fixture(legacyV1Yaml());
-  const registry = new WorkspaceRegistry(config(join(remote.root, "registry"), remote.remote));
-  await registry.bootstrap();
-
-  await expect(registry.acquireSessionRevision("psd-clinical")).rejects.toMatchObject({
-    code: "workspace_invalid",
-  });
-});
-
-test("lists a schema v2 descriptor as migration_required and refuses to acquire it", async () => {
-  const remote = await fixture(legacyV2Yaml());
-  const registry = new WorkspaceRegistry(config(join(remote.root, "registry"), remote.remote));
-  await registry.bootstrap();
-
-  await expect(registry.list()).resolves.toMatchObject([
-    { id: "psd-clinical", state: "migration_required" },
-  ]);
-  await expect(registry.acquireSessionRevision("psd-clinical")).rejects.toMatchObject({
-    code: "workspace_invalid",
-  });
-  await expect(registry.readPinned("psd-clinical", remote.initialCommit)).rejects.toMatchObject({
-    code: "workspace_invalid",
-  });
-});
-
 test("lists operational descriptors retained after their workspace was removed from the active revision", async () => {
   const remote = await fixture();
   const root = join(remote.root, "registry");
diff --git a/backend/test/workspaces-schema.test.ts b/backend/test/workspaces-schema.test.ts
index 2b6f971f..66ce210a 100644
--- a/backend/test/workspaces-schema.test.ts
+++ b/backend/test/workspaces-schema.test.ts
@@ -1,13 +1,12 @@
 import { readFileSync } from "node:fs";
 import { resolve } from "node:path";
+import { parse } from "yaml";
 import { expect, test } from "vitest";
 import * as workspaceSchema from "../src/workspaces/schema.js";
 import {
   parseWorkspaceYaml,
   serializeWorkspaceYaml,
-  validateCanonicalWorkspace,
   validateWorkspaceDescriptor,
-  type WorkspaceDescriptor,
 } from "../src/workspaces/schema.js";
 
 export const validYaml = `workspace:
@@ -165,8 +164,8 @@ test("rejects legacy semantic connector fields and diagnostics in schema v3", ()
   ))).toThrow(/unrecognized key|vector_rest/i);
 });
 
-test("keeps v1 and v2 descriptors parseable but non-operational", () => {
-  const v1Yaml = `workspace:
+test.each([
+  ["v1", `workspace:
   schema_version: 1
   id: psd-clinical
   name: Policlinico San Donato
@@ -192,8 +191,8 @@ semantic_index:
 llm_policy:
   allowed:
     - zai/glm-5.2
-`;
-  const v2Yaml = `workspace:
+`],
+  ["v2", `workspace:
   schema_version: 2
   id: psd-clinical
   name: Policlinico San Donato
@@ -221,22 +220,17 @@ semantic_index:
 llm_policy:
   allowed:
     - zai/glm-5.2
-`;
+`],
+])("rejects schema %s descriptors at parser and object-validator boundaries", (_version, yaml) => {
+  expect(() => parseWorkspaceYaml(yaml)).toThrow(/schema_version|invalid literal|3/i);
+  expect(() => validateWorkspaceDescriptor(parse(yaml))).toThrow(/schema_version|invalid literal|3/i);
+});
 
-  const v1 = parseWorkspaceYaml(v1Yaml);
-  const v2 = parseWorkspaceYaml(v2Yaml);
-  const isOperationalWorkspace = (workspaceSchema as { isOperationalWorkspace?: unknown }).isOperationalWorkspace;
+test("does not expose the redundant canonical validator or v1 migration", () => {
+  const legacyExports = workspaceSchema as Record<string, unknown>;
 
-  expect(v1.workspace.schema_version).toBe(1);
-  expect(v2.workspace.schema_version).toBe(2);
-  expect(validateCanonicalWorkspace(parseWorkspaceYaml(validYaml))).toMatchObject({
-    workspace: { schema_version: 3 },
-  });
-  expect(() => validateCanonicalWorkspace(v1)).toThrow(/schema version 3|migration/i);
-  expect(() => validateCanonicalWorkspace(v2)).toThrow(/schema version 3|migration/i);
-  expect(isOperationalWorkspace).toBeTypeOf("function");
-  expect((isOperationalWorkspace as (workspace: WorkspaceDescriptor) => boolean)(v1)).toBe(false);
-  expect((isOperationalWorkspace as (workspace: WorkspaceDescriptor) => boolean)(v2)).toBe(false);
+  expect(legacyExports.validateCanonicalWorkspace).toBeUndefined();
+  expect(legacyExports.migrateWorkspaceV1ToV2).toBeUndefined();
 });
 
 test("constructs diagnostic URLs only when the resolved URL remains on the service origin", () => {